The present invention relates to a photosensitive polymer containing an azide aryl group as the photocrosslinkable sensitive group, and a photosensitive material for photomechanical process which is prepared by incorporating the said photosensitive polymer with a sensitizing agent. The photosensitive material of this invention is particularly useful for planographic printing.
In Japanese Patent Publication Nos. 47-1167 (1972) and 52-7364 (1977) the blend of a condensate of diazonium salt of p-aminodiphenylamine with formaldehyde and a copolymer of acrylate compounds is disclosed. This blend is known as a typical example among negative photosensitive polymers for planographic printing which are in wide use because of their comparatively good stability during prolonged storage. These photosensitive polymers, however, give printing images which have poor acceptability of printing ink, and plates made from them cause a great deal of spoilage at the beginning of printing work. In addition, such plates have printing images which are mechanically too weak to stand a long run. Moreover, such conventional photosensitive polymers need an aqueous alkaline solution for development and after washing with water, the alkaline solution generates, a large quantity of alkaline waste liquid which has to be treated before being discharged from the working area.
Photosensitive polymers based on a polyhydric alcohol ester of unsaturated acid or polycarboxylic acid were proposed in Japanese Patent Publication Nos. 54-37522 (1979) and 48-2042 (1973) to overcome these drawbacks. They, however, are still not satisfactory.